Two juvenile lowland gorillas (Gorilla gorilla gorilla) experienced polyarthropathies subsequent to Shigella flexneri enteritis. The clinical sign of lameness and soft tissue swelling resolved with anti-inflammatory and antibiotic therapy. One of the animals had a major histocompatibility class I allele with some sequence similarity to HLA-B27. This allele is associated with postinfection reactive arthritis in humans. Key Words Gorilla, arthritis, arthropathy, Shigella, reactive arthritis